Proper earthing is not optional in a solar installation — it is the difference between a fault that trips a breaker and a fault that kills someone. Yet it is one of the most frequently underspecified parts of a solar installation in the Philippines. Many installers use whatever wire is left over rather than applying the correct sizing standard.
The AS/NZS 3000 and PEC 2017 earthing tables are based on IEC metric sizes: 1.5, 2.5, 4, 6, 10, 16, 25mm². But the Philippines commonly uses a different set of wire sizes derived from AWG conversions:
| Philippine Size | Approx. AWG | IEC Equivalent (round up to) | Required Earth Wire (Cu active) |
|---|---|---|---|
| 2.0 mm² | 14 AWG | 2.5 mm² | 2.5 mm² |
| 3.5 mm² | 12 AWG | 4 mm² | 2.5 mm² |
| 5.5 mm² | 10 AWG | 6 mm² | 2.5 mm² |
| 8 mm² | 8 AWG | 10 mm² | 4 mm² |
| 14 mm² | 6 AWG | 16 mm² | 6 mm² |
| 22 mm² | 4 AWG | 25 mm² | 6 mm² |
| 30 mm² | 2 AWG | 35 mm² | 10 mm² |
| 38 mm² | 1 AWG | 50 mm² | 16 mm² |
| 60 mm² | 1/0 AWG | 70 mm² | 25 mm² |
| 80 mm² | 2/0 AWG | 95 mm² | 25 mm² |
The earth electrode (grounding rod) must be a minimum 5/8 inch (16mm) diameter × 1.8m length copper-clad steel rod driven into the ground. In high-resistivity soil (rocky areas in Rizal, Cavite highlands, Benguet), two rods may be required separated by at least 1.8m. The target earth resistance is less than 5 ohms — measured with an earth resistance tester, not a multimeter.
Use the free Earthing Conductor Sizing calculator at solarenergyph.shop — type any Philippine wire size (3.5, 5.5, 8, 14mm², etc.) and get the correct earth wire size instantly per AS/NZS 3000.
Engr. Jason Morales — Founder, SolarEnergyPH